1. Field of the Invention
The present invention relates to a communication device, a reader/writer device, a communication system, and a communication method.
2. Description of the Related Art
In recent years, close-proximity communication in which contactless wireless communication over a short distance is performed with an IC (Integrated Circuit) card has been used for electronic commuter passes and electronic money, for example. Thus, electronic commuter passes that use close-proximity communication and mobile phones with an electronic money function have come into widespread use. Close-proximity communication is standardized in, for example, ISO/IEC 14443 and ISO/IEC 18092 (hereinafter also referred to as NFC (Near Field Communication)).
Exemplary communication modes for performing communication that complies with the NFC standards include communication modes called Type A, Type B, and Type C. Type C is adopted for an IC card system called FeliCa® of Sony Corporation that is the applicant of the present application.
By the way, in the aforementioned Type C, a carrier of 13.56 MHz is adopted, and close-proximity communication is performed at a communication rate of 212 kbps (kilo bit per second) or 424 kbps. Meanwhile, in Types A and B, close-proximity communication is performed at a communication rate of 106 kbps, which is lower than the communication rate of Type C. As described above, as the communication rate of NFC is about several hundred kbps, which is not very high, NFC is not considered to be suitable for transmission of large-volume data such as image contents.
Meanwhile, NFC allows mutual authentication to be performed by identifying a communication party only by passing an IC card over an R/W (Reader/Writer). Thus, there has been proposed a handover in which communication is performed first with NFC, and thereafter the communication mode is switched to a communication mode with a communication rate that is higher than the communication rate of NFC, such as a wireless LAN or Bluetooth® (for example, see JP 2009-218845A).
By the way, recently, close-proximity communication with a communication rate that is higher than the communication rate of NFC has come into widespread use. TransferJet™ is one exemplary communication mode of such high-speed close-proximity communication. In TransferJet™, a carrier of 4.48 GHz is adopted, and close-proximity communication is performed at a maximum communication rate of 560 Mbps.
When TransferJet™ described above is applied to an IC card system, an IC card and an R/W, which reads data from and writes data to the IC card, would be able to rapidly transfer large-volume data such as image contents to each other.
When a communication mode of high-speed close-proximity communication such as TransferJet™ is applied to an IC card system, each of an R/W and an IC card would be able to identify its communication party only by passing the IC card over the R/W without using a handover. Thus, rapid transfer of large-volume data such as image contents is possible.
Meanwhile, JP 2003-284137A describes a technique in which a first communication mode such as PDC (Personal Digital Cellular) and a second communication mode such as W-CDMA (Wideband-Code Division Multiple Access) are used, and if the second communication mode becomes not available, communication with the first communication mode is presumed to start. In addition, JP 2005-117551A describes a technique in which a mobile communication terminal within a service area promptly determines if services of a base station are available so as to reduce the instantaneous interruption time of communication that would be caused by a handover or the like.